Filter packs and methods of manufacture



Patented May 8, 1945 FILTER PACKS AND METHODS OF MANUFAUIURE WalterKasten, Franklin, Mlch., assignor, by

mesne assignments, to Ralph L. Skinner, De-

troit, Mich.

No Drawing. Application April 22, 194 2, Serial-{Na 440,054

12 Claims.

The present invention concerns certain features of, novelty andbetterment in filter-packs and their modes of production, each such packcon-' sisting of, or comprising, a series of relatively-thin discsstacked together face-to-face in a pile or group, and usually aperturedin registration,

whereby the filtering action may take place through the shallow spacesbetween the discs or sheets rather than through the material of thediscs themselves' Heretofore, such packs have ordinarily been made ofpaper discs impregnated with a suitable material, which has been heatedat a suitable temperature, to assure that such material, and thesubstance of the treated discs themselves, will not be detrimentallyafiected by whatever medium, and its polluting contaminants, is toundergo the filtering action.

According to prior practice, the discs have been punched out of aplurality, for instance four, of superposed sheets of paper resting onone another and charged with a phenolic-resin, such as Beckaphene,whereupon a group of such discs has been more or less loosely mounted ona rod, and heat treated in an oven to modify 'or polymerize theBeckaphene, and, thereafter, subsequent to pressing and holding thediscs together, as an assembly, the exterior cylindrical surface of thegroup or row of discs has been ground and polished to provide a smoothouter surface to preclude an undue amount of solid particles filteredout from adhering to such surface, the filtering action occurringordinarily inwardly, but not' necessarily inwardly, of the pack betweenthe discs.

It has been discovered, however, that such procedure and the resultingpack are subject to substantial improvements in that the method may besimplified, the grinding and polishing step may be enough to require thefinal polishing action ferred to; A

It has been determined that to avoid the presence of such objectionabletype of edges, the

discs may be punched out of a single sheet of paper, so that all discsare provided by direct cooperation of the sharp edges of the punch anddie with merely a single sheet of paper or'equivalent or comparablematerial between them, that is, by

omitted in some cases, the pack may be more easily handled, thefiltering action may take place at a lesser pressure on the materialundergoing filtration than has heretofore been permissible, thefiltration occurs with greater uniformity, and cleaning of the pack isrequired less frequently.

To obtain these and other desirable objects and aims, the followingalternative procedures have been invented.

When, in following the earlier process, the discs have been punched outof a plurality of sheets of paper resting on one another in apunch-press, it has been discovered that the edges of the discs, or atleast of a suflicient number of them, have been slightly rough and/orrounded transversely, but

avoidance of a plurality of superimposed paper sheets between them.

Any other appropriate manner, if there be such, of providing sharp,smooth-edged discs may be used to attain the required stated result.

According to the prior art outlined above, when the discs were looselymounted on the rod, to allow the heated air to reach them easily,extended through their aligned or registered apertures, some of thediscs, in fact a substantial percentage of them, in some cases, becomemore or less miscellaneously turned angularly around their axis so thatthe substantially-parallel ridges or rugosities of the crepe-paper ofwhich they were made become disposed in a number of different angularrelations with the surface ribs or rugositles of their companion discson opposite sides thereof with the result that, in the final completepack, the spaces between the surfaces of contacting discs were notexactly uniform, their detrimental deviation therefrom depending, insubstantial measure, upon the angular relation of the discs with oneanother.

To obtain greater uniformity in the thickness of the shallow filteringgaps between the discs, in carrying out the new method, the discs of thepack are mounted on the rod, not in the specified loose hit or misscondition, but held pressed together lengthwise the pack, withmaintenance of the angular relation of all of the discs substantiallythe same, that is to say, with their surface ridges or ribs practicallyparallel to one another, and the heat treatment is applied to the discswhile retained in this pressure contact relation.

The result is that the impregnating material, Beckaphene (40% to fromwhich the alcohol has evaporated, undergoing the heat polymerizationcements or adheres the discs together more or less at the points wherethe ridges of one face contact with those of the adjacent face of thenext disc, and thus all of the discs become adhered together forming asingle unit, stack or assemblage of the numerous discs.

It is to be noted that such adherencetakes place only between parts ofthe ribs, leaving the channels between such ribs open to allow thefiltering flow or passage therethrough of the medium. liquid or gaseous,undergoing purification by the filtration.

Under such heat-treatment, which may be from about 325 F. to about 450F. for approximately six hours to approximately ten minutes,respectively,

' the phenolic-resin becomes modified or polymerized and the paper mayalso undergo substantial change, and, in fact, if the heating iscontinued long enough and at a suitable temperature, the paper may bedisintegrated or converted into carbon leaving the resin with which itwas charged with suitable interstices through which the liquid or gasbeing filtered finds its way from without the pack into its internalpassage formed by the registered apertures of the original paperdiscs.

Thus the final filter-pack has an outer surface, in many cases,adequately smooth so as not inevitably to need the former polishingaction, the pack may possess sumcient lengthwise elasticity, inherent inthe ridges of the discs, so that, in some cases, no supplementalpressure-applying-means.

such as a spring Or terminal rubber washer, or

other resilient or elastic means, is required, the

pressure imposed before the heat treatment being still present in thepack, this resiliency being provided by that of the numerous rugositieswhich are only in part cemented together.

In addition, the thus adhered finished discs now constitute a unitarymember which may be easily handled, as contrasted with a pack of looseuncemented discs, for mounting in a filter-housing, and for replacementby a new pack when necessary,

It should be clear that the discs may be of any suitable size andappropriate shape, that the original discs may be of paper or otherbefitting material, and that the impregnating or conditioning agent maybe any which will perform the essential functions.

It is not to be understood that the surface ribs or ridges of each discare necessarily all parallel to one another, because the invention isalso applicable to discs having roughnesses of various and miscellaneouskinds.

Where crepe-paper discs, having the ribs or ridges of each substantiallyparallel, are used, the ribs of contactingdiscs need not be absolutelyparallel to one another, since a slight progressive deviation therefromproduces results practically the same as when precise parallelism ispresent, so that in such a non-parallel pack the ribs or ridges of thetwo terminal discs may be even at right-angles to one another or at someintermediate angular relation.

As an alternative or supplementary procedure, which in many cases ispreferable, after providing the stack of treated, registered discs heldpressed together on the rod, or its equivalent, and prior to the heatpolymerizing treatment, the stack is painted with, sprayed with, ordipped into a dilute solution of the Beckaphene, such as approximately5% Beckaphene and 95% alcohol. and. thereafter, the stack is subjectedto the heat treatment to polymerize the Beckaphene, thus rendering thepack immune to the action of the fluid to be filtered and also exemptfrom any detrimental effect thereon by the one or more contaminants insuch fluid.

After such polymerization, the exterior of the pack is smoothed andpolished to a high degree of uniformity and evenness, thus, insubstantial measure, reducing the tendency of the filteredout particlesto cling or adhere to such surface.

2,375,240 The specified thin Beckaphene solution does not fill up orseal the interstices of the pack, but it does something to the materialof the pack which enables it to take on a high polish.

Why such application of this solution to the pack does not close itscavities and passages and ,why it permits the pack to be polished to thehigh degree which it does, is not fully known at the present time.

As will be readily understood, the shape ofthe pack may be anythingdesirable; it.need not be cylindrical.

Those acquainted with this art will readily understand that theinvention herein set forth is not necessarily limited and restricted tothe precise and exact details presented and that various changes andmodifications may be resorted to without departure from the invention asdelined by the appended claims and without the loss 'or sacrifice ofanyof its material benefits and advantages.

I claim: I

1. In a known type of edge-filtration filterpack composed of a series ofregistered face-toface contacting layers of {an uneven-surface material,the pores of which material are closed by an impregnating-agentunaffected by the me- ,clium to be filtered Or by any of itscontaminants,

the novel improvement of a cementitious-medium adhering the contactingsurfaces of said layers together sumciently to constitute a unit, yetpermitting the filtrate to pass between such surfaces during theedge-filtration.

2. The novel improvement in a filter-pack as set forth in claim 1, inwhich said impregnatingagent is also the cementitious-medium whichadheres said layers together.

3. The novel improvement in a filter-pack as set forth in claim 1, inwhich said material is crepe-paper.

4. The novel improvement in a filter-pack as set forth in claim 1, inwhich said material is crepe-paper and in which the impregnatingagent isalso the cementitious-medium which adheres said layers together.

5. The novel improvement in a filter-pack as set forth in claim l,-including the additional novel feature that the exterior surface of saidpack is polished.

6. The novel improvement in an edge-filtration filter-pack as set forthin claim 1, in which said material is crepe-paper withsubstantiallyparallel surface rugosities, and in which the rugosities ofthe several layers are substantiallyparallel.

7. The novel improvement in an edge-filtration filter-pack as set forthin claim 1, in which said material is crepe-paper withsubstantiallyparallel surface-rugosities, in which the rugosities of theseveral layers are substantiallyparallel, and in which saidimpregnating-agent is also the cementitious-medium which adheres thelayers together.

8. In the known process of making an edgefiltration filter-packincluding the registering of a series of layers of an uneven-surfacematerial in face-to-face contact with one another, the pores of saidmaterial being closed by a polymerizable impregnating-agent which, whenpolymerized, is unaffected by the medium to be illtered or by any of itscontaminants, and then polymerizing said agent, the novel improvement ofholding said impregnated layers pressed together face-to-face duringsuch polymerization to cause sufllcient adhesion of said layers togetherby the polymerized-agent to constitute a unit while at the same timeleaving spaces enough between the adhered surfaces to allow the filtrateto flow therethrough during the edge-filtration.

9. The novel improvement in the process of making an edge-filtrationfilter-pack as set forth in claim 8, including the additionalcombination of novel improvements of coating the surface of said ackbefore the polymerizingstep with an agent having comparable properties,and polishing such coated surface after said polymerizin step.

10. The novel improvement in the process of making an edge-filtrationfilter-pack as set forth in claim 8, in which said material iscrepe-paper with substantially-parallel surface-rugosities,

and in which the rugosities of the several layers,

are substantially-parallel during the polymerization, v

11. The novel improvement in the process of making an edge-filtrationfllter pack as set forth in claim a, in which said material is paperwith Y surface-ribs, and in which said ribs are not completely flattenedout while the layers are held pressed together during thepolymerization.

12. In the known process of making an edgefiltration filter-packincluding the mounting'of a series of layers of uneven-surface materialin register with, and in face-to-face contact with,

20 spaces between said layers.

WALTER KASTEN.

